<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="content-type" content="text/html;charset=UTF-8" />  
    <title>第一个网页</title>
</head>
<body>
    <div style="width: 200px;background-color: red;height: 200px;">
        一
        <div style="width: 100px;background-color: green;height: 100px;">
            B
            <div style="width: 40px;background-color: yellow;height: 40px;position: absolute;
            left:10px;top: 10px;">
                B1
            </div>
            <div style="width: 30px;background-color: orange;height: 30px;">
                B2
            </div>
        </div>
        <div style="width:150px;background-color: blue;height: 150px;">
            C
        
        </div>
    </div>
    
</body>
</html>